Question for Today What are the different niches that organisms can occupy in an aquatic ecosystem? How are marine ecosystems organized? How are freshwater systems organized? What are the differences between an oligotrophic and eutrophic lake? How do humans affect marine and freshwater ecosystems?

Aquatic life zones and niches Aquatic life zones are similar to terrestrial biomes. Instead of looking at temperature and precipitation, aquatic life zones classify by salinity.

Aquatic life zones and niches Two major life zones: Saltwater or marine Oceans Estuaries and coastal wetlands Shorelines, coral reefs and mangrove forests Freshwater Lakes, rivers, streams and inland wetlands

Aquatic Life Zones and Niches Aquatic systems contain floating, drifting, swimming, bottom-dwelling, and decomposer organisms. Plankton: important group of weakly swimming, free- floating biota. Phytoplankton (plant), Zooplankton (animal), Ultraplankton (photosynthetic bacteria) Nekton: fish, turtles, whales. Benthos: bottom dwellers (barnacles, oysters). Decomposers: breakdown organic compounds (mostly bacteria).

Phytoplankton Description – small drifting plants Niche – they are producers that support most aquatic food chains Example – cyanobacteria & many types of algae

Zooplankton Description – herbivores that feed on phytoplankton or other zooplankton Niche – food stock for larger consumers Example – krill; small crustaceans

Nekton Description – larger, strong- swimming consumers Niche – top consumers in the aquatic ecosystem Example – fish, turtles, and whales

Benthos Description – bottom-dwelling creatures Niche – primary consumers, decomposers Example – barnacles, oysters, and lobsters

Marine Life zones Most Marine Life Zones are organized by depth/light penetration, and distance from the shore Three zones based off distance from the shore Intertidal zone, Coastal Zone and the Open Sea Three Zones based off depth/light penetration Euphotic Zone Bathyal Zone Abyssal Zone

Fig. 8-5, p. 166 Low tide Coastal Zone Open Sea Depth in meters High tide Sun Sea level 50 Estuarine Zone Euphotic Zone 100 Photosynthesis Continental shelf 200 Bathyal Zone 500 1,000 Twilight 1,500 Water temperature drops rapidly between the euphotic zone and the abyssal zone in an area called the thermocline. Abyssal Zone 2,000 3,000 4,000 Darkness 5,000 10, Water temperature (°C)

Freshwater Ecosystems Freshwater Ecosystems are organized in a similar way to Marine Ecosystem Two types of Freshwater Ecosystems Lentic (Standing) Lakes, Ponds, inland wetlands Lotic (Flowing) Rivers, Streams

Lakes Lakes are large natural bodies of standing freshwater formed when precipitation, runoff, or groundwater seepage fills a depressions in earth’s surface. Can be caused by glaciation, crustal displacement, and volcanic activity Lakes are stratified due to Light Penetration and Temperature. Littoral Limnetic Profundal Benthic

Fig. 8-15, p. 175 Sunlight Painted turtle Blue-winged teal Green frog Muskrat Pond snail Littoral zone Plankton Limnetic zone Profundal zone Diving beetle Benthic zone Northern pike Yellow perch Bloodworms

Oligotrophic vs. Eutrophic Ecologist can also classify lakes according to nutrient content and primary productivity. Two Types: Oligotrophic Lakes Low Nutrient, Low Productivity Crystal-clear water Small population of phytoplankton and fish. Eutrophic Lakes High Nutrient, High Productivity High Turbidity, murky-brown or green water

How do Humans affect marine biomes? Major threats to marine systems Coastal development Overfishing Runoff of nonpoint source pollution Point source pollution Habitat destruction Introduction of invasive species Climate change from human activities Pollution of coastal wetlands and estuaries

How do Humans effect freshwater ecosystem? Impact of dams and canals on rivers Impact of flood control levees and dikes along rivers Impact of pollutants from cities and farms on rivers Impact of drained wetlands